3 bit input(A,B,C) 7 segment display help

Discussion in 'Homework Help' started by Ajdawson94, Nov 19, 2018.

  1. Ajdawson94

    Thread Starter New Member

    Nov 19, 2018
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    HI im a first year student and im only just starting out, in the examples my professor gave me he uses bcd inputs A,B,C,D to come up with a truth table standard 0-9 display, however i have been asked to use a 3 bit input to draw a truth table for a 7 segment display that spells the word BLUEFISH. how would the actual truth table to drive segments a-g look like? would it look like this? bluefish.jpg

    truth table.jpg
    any help is greatly appreciated
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    As an example, which segments must be lit to show "F"?
     
  3. bertus

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    Apr 5, 2008
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  4. dl324

    AAC Fanatic!

    Mar 30, 2015
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    Welcome to AAC!
    That's one possible implementation. If you ever have the chance of needing to display the number 8, you might choose a different combination of segments for B.

    Since this is homework, you need to show your work before we can attempt to guide you to a solution
     
  5. Ajdawson94

    Thread Starter New Member

    Nov 19, 2018
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    it says to Draw the truth table to drive segments (a-g) of the display. then Using the truth table you have obtained, draw Karnaugh maps for each segment to find the minimised logic expression. i can do the karnaugh maps and find the expression yet the truth table is giving me issues.
    each letter of the BLUEFISH corresponds 0-7 in decimal digit.
    0->’B’, 1->’L’, 2 ->’u’, 3-> ‘E’, 4->’F’, 5->’i’, 6->’S’, 7->’h
    so digit 0 needs all segments lit to produce B and so on.

    from that i produced the table in my original post, with it being 3 bit input would i be correct in assuming that i only do a,b,c and not the standard 4 bit BCD a,b,c,d.
    i know that B can be shown in an alternative format however i have been asked to do so as shown in the image
     
    Last edited: Nov 19, 2018
  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The give table is not complete.
    I would use the leading zeros too.
    You could do this by placing A, B and C in separate coloms.

    Bertus
     
  7. dl324

    AAC Fanatic!

    Mar 30, 2015
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    You didn't state that requirement in the first post. It would be helpful if you posted the complete text for the problem.
     
  8. WBahn

    Moderator

    Mar 31, 2012
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    You have seven different logic problems. You have one logic for each segment. Treat them as separate 3-input, 1-output logic problems. Don't make it harder than it is.
     
  9. Ajdawson94

    Thread Starter New Member

    Nov 19, 2018
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    thanks i think i get it now thankyou all for the help
     
  10. absf

    AAC Fanatic!

    Dec 29, 2010
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    Wouldn't it look better in All Caps?
    BLUE FISH.PNG
     
    dl324 likes this.
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